Extruder with feed block for promoting increased mass transport rate

ABSTRACT

A feeder for an extruder includes a feed flow passage extending in an axial direction from a feeder inlet to a feeder outlet, and an axially extending rotatable screw provided in the feed flow passage. Rotation of the screw draws a feedstock in a direction of flow to the feeder outlet. The feeder inlet has an inlet passage that overlies the screw. The inlet passage has a width in a plane transverse to the axial direction, and the width decreases in the direction of flow.

FIELD

This disclosure relates generally to extruders, and more specifically toextruders for extruding a plastic or thermoplastic material. Thisdisclosure also relates to using one or more extruders to produce anextruded or molded plastic part.

INTRODUCTION

Extruders are typically used to heat and melt a solid input material(e.g. a plastic, or thermoplastic material) and extrude the material ina flowable, or melted state. The extruded, or output, material may bedirected through a form or die while it cools and solidifies to form anelongate plastic component having a cross-sectional profile defined bythe form or die. Alternatively, the output material may be directed intoa mold where it is then cooled and solidifies to form a molded componenthaving a shape defined by the mold.

One source of the heat provided to raise the temperature of the conveyedplastic material as it passes through the extrusion or injection barrelis mechanical shear heating. In shear heating, the plastic material issubjected to shearing or stretching between a rotating screw and astationary barrel, often while under relatively high pressures (e.g.2,000 pounds per square inch (psi), up to 30,000 psi or higher), causingheat to develop in the material. Typically, shear heating is asignificant source of heat. For example, shear heating may provide about70% or more (e.g., 80%, 90%) of the heat required to melt the plasticmaterial.

SUMMARY

The following introduction is provided to introduce the reader to themore detailed discussion to follow. The introduction is not intended tolimit or define any claimed or as yet unclaimed invention. One or moreinventions may reside in any combination or sub-combination of theelements or process steps disclosed in any part of this documentincluding its claims and figures.

In accordance with one aspect of this disclosure, a feed block for anextruder is configured to promote an increased mass transport rate offeedstock material through the feed block and into the barrel of theextruder. An increased mass transfer rate through the feed block mayallow more material to be transferred into the barrel for a given unitof time. Accordingly, more material per unit time can be output from theextruder.

In accordance with this aspect, the geometry of the feeder inlet of thefeed block may be configured to promote compression, e.g. tangentialcompression, of the material as it is directed into and along the lengthof the feed flow passage. Accordingly, plastic material being conveyedthrough the feed block may be subjected to increasing pressures as ittravels towards and into the extrusion barrel. An advantage of thisdesign is that there may be less hold-up of material in the feed blockand a more uniform flow of material into the extrusion barrel.

Optionally, the feed block may removably receive different feederinserts. Providing a removable feeder insert may have one or moreadvantages. For example, a first feeder insert may have a first inletpassage and the second feeder insert may have a second inlet passagehaving a different configuration to the first inlet passage. Thus, aparticular feeder insert may be selected based on the composition of theinput material being extruded and/or based on operating parameters (e.g.temperature, screw RPM, barrel pressure) of the extrusion process.

In accordance with this broad aspect, there is provided a feeder for anextruder, the feeder comprising:

-   -   (a) a feed flow passage, the feed flow passage extending in an        axial direction from a feeder inlet to a feeder outlet;    -   (b) an axially extending rotatable screw provided in the feed        flow passage, wherein rotation of the screw draws a feedstock in        a direction of flow to the feeder outlet; and,    -   (c) the feeder inlet has an inlet passage that overlies the        screw, the inlet passage has an upper end, a lower end adjacent        the screw, a length in the axial direction, a width in a plane        transverse to the axial direction, and a depth extending between        the upper and lower ends of the inlet passage, wherein the width        decreases in the direction of flow.

In some embodiments, the feeder may further comprise a hopper having ahopper outlet and the feeder inlet may be provided below the hopperoutlet.

In some embodiments, the feeder may further comprise a cooling member.

In some embodiments, the cooling member may comprise cooling channelsprovided in thermal communication with the feed flow passage.

In some embodiments, the feeder may further comprise a feeder insertthat may be removably mounted in a feed throat of the feeder, whereinthe feeder insert has the inlet passage.

In some embodiments, the feeder may removably receive different feederinserts, wherein a first feeder insert may have a first inlet passageand the second feeder insert may have a second inlet passage wherein thesecond inlet passage may have a different configuration to the firstinlet passage.

In some embodiments, each inlet passage may have an upstream end in thedirection of flow through the feed flow passage and a downstream end inthe direction of flow through the feed flow passage and the second inletpassage may have a narrower width at the downstream end of the inletpassage than the first inlet passage.

In some embodiments, the lower end of the inlet passage may have aninner wall facing the screw and the inner wall may be spaced from theouter end of the screw by a distance, wherein the distance may decreasein the direction of rotation.

In some embodiments, the width may decrease at a constant rate in thedirection of flow.

In some embodiments, the width may decrease at an increased rate in thedirection of flow.

Additionally or alternatively, in accordance with this aspect, thegeometry of an internal feed flow passage of the feed block may beconfigured to promote an increasing volumetric compression as materialis directed into and along the length of the feed flow passage.Accordingly, plastic material being conveyed through the feed block maybe subjected to increasing pressures as it travels towards and into theextrusion barrel.

In accordance with this broad aspect, there is provided a feeder for anextruder, the feeder comprising:

-   -   (a) a feed flow passage, the feed flow passage extending in an        axial direction from a feeder inlet to a feeder outlet;    -   (b) an axially extending rotatable screw provided in the feed        flow passage, wherein rotation of the screw draws a feedstock in        a direction of flow to the feeder outlet; and,    -   (c) the feeder inlet has an inlet passage that overlies the        screw, the inlet passage has an upper end, a lower end adjacent        the screw, a length in the axial direction, a width in a plane        transverse to the axial direction, and a depth extending between        the upper and lower ends of the inlet passage,    -   wherein the lower end of the inlet passage has an inner wall        facing the screw and the inner wall is spaced from the outer end        of the screw by a distance, wherein the distance decreases in        the direction of rotation.

In some embodiments, the feeder may further comprise a hopper having ahopper outlet and the feeder inlet may be provided below the hopperoutlet.

In some embodiments, the feeder may further comprise a cooling member.

In some embodiments, the cooling member may comprise cooling channelsprovided in thermal communication with the feed flow passage.

In some embodiments, the feeder may further comprise a feeder insertthat may be removably mounted in a feed throat of the feeder, whereinthe feeder insert may have the inlet passage.

In some embodiments, the feeder may removably receive different feederinserts, wherein a first feeder insert may have a first inlet passageand the second feeder insert may have a second inlet passage wherein thesecond inlet passage may have a different configuration to the firstinlet passage.

In some embodiments, the width may decrease in the direction of flow andeach inlet passage may have an upstream end in the direction of flowthrough the feed flow passage and a downstream end in the direction offlow through the feed flow passage and the second inlet passage may havea narrower width at the downstream end of the inlet passage than thefirst inlet passage.

In some embodiments, the distance may decrease at a constant rate in thedirection of flow.

In some embodiments, the distance may decrease at an increased rate inthe direction of flow.

In accordance with another aspect of this disclosure, two or moreextruders may be used to concurrently fill a mold in a molding process.Plastic material output from the extruders, which is in a flowable ormelted state, is directed into a common mold, either directly or via amanifold or heated flow conduit connected to the mold and to at leastsome of the extruders.

By concurrently using the output from two or more extruders, arelatively large total flow rate of material may be provided to a moldwithout requiring an extruder with a relatively high operating pressureand/or flow rate. For example, a molding process using smaller, lightweight extruders (e.g., bench top extruders each weighing under 500 lbs,400 lbs, or 300 lbs) may be ‘scaled up’ to provide higher moldingvolumes (e.g. for use with molds for relatively large molded components)by providing more extruders, e.g. without having to ‘scale up’ the flowrate and/or operating pressure of any one extruder.

To facilitate the concurrent use of two or more extruders, in someembodiments it may be advantageous to provide apparatus in which thefeed inlets of two or more extruders are not axially aligned with eachother. For example, two or more of a plurality of extruders may have adifferent respective axial length. Additionally, or alternatively, oneor more extension conduits may be provided between the output nozzle ofat least one of the extruders and the common mold. Alternatively, or inaddition, the outlet nozzles of two or more extruders may be provided atstaggered locations axially along the length of a flow conduit, which isoptionally heated, in communication with a mold.

In accordance with this broad aspect, there is provided a moldingapparatus comprising:

-   -   (a) a plurality of axially extending extruders wherein each of        the extruders is fluidly connectable with a common mold whereby        the mold is concurrently filled from each of the extruders; and,    -   (b) each of the extruders has a feed inlet,    -   wherein the feed inlets are axially spaced from each other.

In some embodiments, at least two of the extruders may have differentaxial lengths.

In some embodiments, the extruders may feed into a common manifold andthe manifold may be connectable to the mold.

In some embodiments, the plurality of axially extending extruders maycomprise two extruders that have a common axial length, each extrudermay have a nozzle outlet and one of the two extruders may furthercomprise a conduit extending from the nozzle outlet to the manifold.

In some embodiments, the at least two of the extruders may furthercomprise an axially extending conduit extending from the extruder to themanifold and the conduits may have differing axial lengths.

In some embodiments, the molding apparatus may further comprise aplurality of hoppers in flow communication with the feed inlets.

In some embodiments, each extruder may have a hopper.

In some embodiments, a common hopper may be provided for at least two ofthe extruders.

In some embodiments, a first extruder may be provided with an additiveand the common manifold may further comprise a mechanical member forblending the output of the first extruder with the output of at leastone other of the extruders.

In another broad aspect, to facilitate the concurrent use of two or moreextruders, a common manifold or conduit may be provided between each ofa plurality of extruders and a common mold. Optionally, such a conduitis heated to maintain the flowable plastic material within the conduitat an elevated temperature so that the plastic material remains in aflowable state until it exits the conduit.

In accordance with this broad aspect, there is provided a moldingapparatus comprising:

-   -   (a) a plurality of axially extending extruders, each extruder        having longitudinally extending axis; and,    -   (b) a heated conduit in flow communication with the plurality of        extruders, wherein the heated conduit is connectable to a mold,        whereby the mold is concurrently fillable from each of the        extruders.

In some embodiments, the heated conduit may have a length extending in adirection of flow from an upstream end of the heated conduit to adownstream end of the heated conduit and at least some of the extrudersare in flow communication with the heated conduit at different locationsalong the length of the heated conduit.

In some embodiments, the axis of at least some of the extruders mayextend at an angle to the direction of flow in the heated conduit.

In some embodiments, an included angle located between the axis of atleast some of the extruders and the direction of flow in the heatedconduit may be up to 90°.

In some embodiments, an included angle located between the axis of atleast some of the extruders and the direction of flow in the heatedconduit may be an acute angle, such as between 15-75° or 30-60°.

In some embodiments, the molding apparatus may further comprise aplurality of hoppers in flow communication with the extruders wherein atleast some of the hoppers may be spaced apart from each other along thedirection of flow.

In some embodiments, each extruder may have a hopper.

In some embodiments, the molding apparatus may further comprise a commonhopper in flow communication with at least two of the extruders.

In some embodiments, a first extruder may be provided with an additiveand the heated conduit may further comprise a mechanical member forblending the output of the first extruder with the output of at leastone other of the extruders.

In some embodiments, the heated conduit may be provided with a feedstockejection assist member.

In some embodiments, the feedstock ejection assist member may comprise aplunger at an upstream end of the heated conduit.

In another broad aspect, an extruder may have a modular design, whichmay allow an extruder to be assembled from (and preferably disassembledinto) a relatively low number of parts or modules. The modular designmay enable the modules to be connected together without the need ofskilled tradespeople. For example, the modules may be designed to beconnected to each other by inserting bolts provided on one module intomating holes provided in another mating module and securing the modulestogether using the bolts and nuts.

A modular extruder design may have one or more advantages. For example,assembly of such an extruder may be relatively simple, which may reducetime and/or cost required to install the extruder on site. Also, amodular design may allow one or more modular components to be providedin different variations, which may allow a large number of extruderconfigurations to be provided by selecting desired combinations ofmodular components.

A further advantage is that an extruder may be able to be repaired bydetaching a broken module and inserting a new or refurbished module,which may be shipped e.g., by commercial courier. For example, eachmodule may weigh under 175 lbs, 150 lbs, 135 lbs, or 100 lbs.Accordingly, the modules may be shipped by commercial courier. Further,they may be manipulatable by a few people without the need of heavyequipment, such as a forklift.

In accordance with this broad aspect, there is provided an extrudercomprising:

-   -   (a) an axially extending extruder barrel module having a        feedstock inlet end and a feedstock outlet end axially spaced        from the feedstock inlet end in a direction of flow through the        extruder barrel module, the extruder barrel module comprising an        axially extending barrel in which an extruder barrel screw is        removably receivable;    -   (b) an axially extending extruder feeder module removably        connectable to the feedstock inlet end of the extruder barrel        module, the extruder feeder module having an axially extending        flow passage aligned with the direction of flow when the        extruder feeder module is connected to the barrel module, the        axially extending flow passage having a feedstock outlet end and        a screw motor module mounting end axially spaced from the        feedstock outlet end of the extruder feeder module in a        direction of flow through the axially extending flow passage;    -   (c) a screw motor module removably connectable to the screw        motor module mounting end of the extruder feeder module, the        screw motor module having a motor drivingly connectable with a        screw in the flow passage of the extruder feeder module; and,    -   (d) an electronics module electrically connectable with the        screw motor module and mechanically removably mounted as part of        the extruder.

In some embodiments, each module may be shippable by a commercialcourier company.

In some embodiments, each module may weigh under 175 lbs, 150 lbs, 135lbs, or 100 lbs.

In some embodiments, the screw in the flow passage may be drivinglyconnectable with the extruder barrel screw when the extruder isassembled.

In some embodiments, the screw in the flow passage and the extruderbarrel screw may comprise a single integrally formed screw.

In some embodiments, the screw in the flow passage and the extruderbarrel screw may be removable as a unitary member from the extruderbarrel module and the extruder feeder module.

In some embodiments, the electronics module may be also electricallyconnectable with the extruder barrel module.

In some embodiments, the electronics module may be also electricallyconnectable with the extruder feeder module.

In some embodiments, the electronics module may be automaticallyelectrically connectable with the screw motor module when theelectronics module is mounted as part of the extruder.

Also in accordance with this broad aspect, there is provided an extrudercomprising:

-   -   (a) an axially extending extruder barrel module having a        feedstock inlet end and a feedstock outlet end axially spaced        from the feedstock inlet end in a direction of flow through the        extruder barrel module, the extruder barrel module comprising an        axially extending barrel in which an extruder barrel screw is        removably receivable;    -   (b) an axially extending extruder feeder module removably        connectable in flow communication with the feedstock inlet end        of the extruder barrel module, the extruder feeder module having        an axially extending flow passage aligned with the direction of        flow when the extruder feeder module is connected in flow        communication with the barrel module, the axially extending flow        passage having a feedstock outlet end and a screw motor module        end axially spaced from the feedstock outlet end of the extruder        feeder module in a direction of flow through the axially        extending flow passage;    -   (c) a screw motor module removably drivingly connectable to an        end of a screw located at the screw motor module end of the        extruder feeder module; and,    -   (d) an electronics module electrically connectable with the        screw motor module and mechanically removably mounted as part of        the extruder.

In some embodiments, each module may weigh under 175 lbs, 150 lbs, 135lbs, or 100 lbs.

In some embodiments, the screw in the flow passage may be drivinglyconnectable with the extruder barrel screw when the extruder isassembled.

In some embodiments, the screw in the flow passage and the extruderbarrel screw may comprise a single integrally formed screw.

In some embodiments, the screw in the flow passage and the extruderbarrel screw may be removable as a unitary member from the extruderbarrel module and the extruder feeder module.

In some embodiments, the electronics module may be also electricallyconnectable with the extruder barrel module.

In some embodiments, the electronics module may be also electricallyconnectable with the extruder feeder module.

It will be appreciated by a person skilled in the art that a method orapparatus disclosed herein may embody any one or more of the featurescontained herein and that the features may be used in any particularcombination or sub-combination.

These and other aspects and features of various embodiments will bedescribed in greater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the described embodiments and to show moreclearly how they may be carried into effect, reference will now be made,by way of example, to the accompanying drawings in which:

FIG. 1 is a perspective view of an extruder in accordance with oneembodiment;

FIG. 2 is a perspective view of the extruder of FIG. 1, with portions ofa controller housing removed;

FIG. 3 is a front view of the extruder of FIG. 1;

FIG. 4 is a rear view of the extruder of FIG. 1;

FIG. 5 is an end view of the output end of the extruder of FIG. 1;

FIG. 6 is an end view of the end longitudinally opposed to the outputend of the extruder of FIG. 1;

FIG. 7 is a top view of the extruder of FIG. 1;

FIG. 8 is a bottom view of the extruder of FIG. 1;

FIG. 9 is a front view of components of the extruder of FIG. 1 in apartially disassembled configuration;

FIG. 10 is a perspective view of an extruder barrel, feed block, hopper,and output nozzle of the extruder of FIG. 1;

FIG. 11 is a perspective cross-section view of the extruder barrel, feedblock, hopper, and output nozzle of the extruder of FIG. 10;

FIG. 12 is a cross-section view of the feed block of the extruder ofFIG. 10 in a vertical plane through the feed block;

FIG. 12B is a cross-section view of an alternative embodiment of anextruder feed block in a vertical plane through the feed block;

FIG. 13 is a perspective section view of the extruder barrel, feedblock, hopper, and output nozzle of the extruder of FIG. 10, taken alongline 13-13 in FIG. 10;

FIG. 14 is a perspective section view of the extruder barrel, feedblock, and hopper of the extruder of FIG. 10, taken along line 14-14 inFIG. 10;

FIG. 15 is another perspective section view of the extruder barrel, feedblock, and hopper of the extruder of FIG. 10, taken along line 14-14 inFIG. 10;

FIG. 16 is a rear perspective view of the extruder barrel, feed block,feed block insert, and extrusion screw of the extruder of FIG. 1

FIG. 17 is an exploded view of the extruder barrel, feed block, feedblock insert, and extrusion screw of FIG. 16;

FIG. 18 is an exploded view of the extruder barrel, feed block, and feedblock insert of FIG. 17;

FIG. 19 is a perspective view of the extruder barrel, feed block, andfeed block insert of FIG. 18;

FIG. 20 is a perspective cross-section view of the extruder barrel, feedblock, and feed block insert of FIG. 19;

FIG. 21 is a top view of the feed block, feed block insert, extruderbarrel, and extrusion screw of FIG. 16;

FIG. 22 is a perspective section view of the feed block, feed blockinsert, extruder barrel, and extrusion screw of FIG. 21, taken alongline 22-22 in FIG. 21;

FIG. 23 is a rear perspective view of the feed block insert of FIG. 21;

FIG. 24 is an end view of the barrel facing end of the feed block insertof FIG. 21;

FIG. 25 is an end view of the end opposite the barrel facing end of thefeed block insert of FIG. 21;

FIG. 26 is a bottom view of the feed block insert of FIG. 21;

FIG. 27 is a perspective view of two extruders coupled to a common mold,in accordance with one embodiment;

FIG. 28 is a perspective view of two extruders coupled to a common mold,in accordance with another embodiment;

FIG. 29 is a perspective view of the output ends of three extruders, inaccordance with one embodiment;

FIG. 30 is a top view of the extruders of FIG. 29;

FIG. 31 is a perspective view of the output ends of two extruders, inaccordance with one embodiment;

FIG. 32 is a top view of the extruders of FIG. 31;

FIG. 33 is an end view of the output ends of the extruders of FIG. 31;

FIG. 34 is a perspective view of six extruders connected to a heatedconduit in accordance with one embodiment;

FIG. 35 is a top view of the six extruders and heated conduit of FIG.34;

FIG. 36 is a perspective section view of the heated conduit of FIG. 34,taken along line 36-36 in FIG. 35;

FIG. 37 is a perspective section view of one of the extruders and theheated conduit of FIG. 34, taken along lines 37-37 and 37′-37′ in FIG.35;

FIG. 38 is a perspective view of six extruders connected to a heatedconduit in accordance with another embodiment;

FIG. 39 is a top view of the six extruders and heated conduit of FIG.38;

FIG. 40 is a perspective view of six extruders connected to a heatedconduit in accordance with another embodiment; and,

FIG. 41 is a top view of the six extruders and heated conduit of FIG.40.

The drawings included herewith are for illustrating various examples ofarticles, methods, and apparatuses of the teaching of the presentspecification and are not intended to limit the scope of what is taughtin any way.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Various apparatuses, methods and compositions are described below toprovide an example of an embodiment of each claimed invention. Noembodiment described below limits any claimed invention and any claimedinvention may cover apparatuses and methods that differ from thosedescribed below. The claimed inventions are not limited to apparatuses,methods and compositions having all of the features of any oneapparatus, method or composition described below or to features commonto multiple or all of the apparatuses, methods or compositions describedbelow. It is possible that an apparatus, method or composition describedbelow is not an embodiment of any claimed invention. Any inventiondisclosed in an apparatus, method or composition described below that isnot claimed in this document may be the subject matter of anotherprotective instrument, for example, a continuing patent application, andthe applicant(s), inventor(s) and/or owner(s) do not intend to abandon,disclaim, or dedicate to the public any such invention by its disclosurein this document.

The apparatuses, methods and compositions may be used to extrude and/ormold various materials, such as a plastic material and optionally athermoplastic material. The thermoplastic material may be one or more ofacrylonitrile butadiene styrene (ABS), polyvinyl chloride (PVC),chlorinated polyvinyl chloride (CPVC), polyethylene (PE), low molecularweight PE, high density PE, ultra high molecular weight PE, polyethyleneterephthalate (PET), polystyrene (PS), polycarbonate (PC), acrylic,polypropylene (PP), polybutylene terephthalate (PBT), polyvinyl acetate,ethylene-vinyl acetate (EVA), or the like. Optionally, the thermoplasticmaterial is one or more of PVC and CPVC.

General Description of Preferred Embodiments Utilizing Combinations ofVarious Aspects

FIGS. 1 to 9 exemplify an extruder, referred to generally as 1000.Extruder 1000 may be used to heat and melt an input material (e.g. aplastic, or thermoplastic material which may be solid) and extrude thematerial in a flowable, or melted state. The extruded, or output,material may be used to fill a mold in a molding process, as will bediscussed further subsequently, or with an extrusion die. It will beappreciated that extruder 1000 may receive any input material known inthe extruder art.

Extruder 1000 may include one or more user input devices that allow auser to initiate and/or control the operation of the extruder. Forexample, user input devices may include one or more of power switches1012, which may be a main on/off switch, and a display 1018, which maybe a touch screen display for enabling user input. Extruder 1000 mayalso include one or more user output devices that allows a user tomonitor the operation of the extruder. For example, the user outputdevice may be display 1018, and/or one or more audio and/or visualoutput devices, such as lights, buzzers, speakers, and the like (notshown).

As shown in FIGS. 1 to 9, at least some of the user input devices and/orcontrol electronics of extruder 1000 may be enclosed in a controlhousing or cabinet 1010, which in the illustrated embodiment includes aplurality of solid panels 1015 and an access door 1017 secured via,e.g., hinges 1019 to provide access to components inside the cabinet. Itwill be appreciated that the housing may be made from any suitablematerial (e.g. metal, plastic, and the like), and that in alternateembodiments the cabinet may be formed of more or fewer panels. In someembodiments, a control cabinet may not be provide.

Extruder 1000 also includes an input member for introducing the materialinto the extruder. The input member may be an input hopper 1020 forreceiving the input material (e.g. a solid pelletized plastic). Asperhaps best seen in FIG. 11, material received in hopper 1020 isdirected through a feed throat 1062 in a feed block 1600 where it isintroduced into the channels of an extrusion screw 1300. Rotation of thescrew 1300 advances or conveys the pelletized input material from afirst, or input, end 1302 of the extrusion screw towards a second, oroutput, end 1304 of the extrusion screw 1300, thereby conveying thematerial through an extrusion barrel 1100 from a first, or input, end1102 of the barrel to a second, or output, end 1104 of the barrel.

As the material is conveyed through the extrusion barrel 1100 by thescrew 1300, heat from one or more (e.g., a plurality of) heatingelements 1110 positioned about the outer surface 1108 of the extrusionbarrel 1100 is transferred through the extrusion barrel wall to theconveyed material via the inner barrel surface 1106, raising thetemperature of the material and thereby causing the material totransition to a flowable, or melted state. It will be appreciated thatheating elements 1100 may be positioned along a portion of, or all of,the length of the barrel. Each heating element may surround a portion ofthe outer perimeter of the barrel or they may surround most or all ofthe outer surface of the barrel. In the example illustrated in FIGS. 1to 9, eight spaced apart heating elements 1110, each of which is annularand surrounds the outer surface of the barrel, are shown. In the exampleillustrated in FIG. 11, five heating elements 1110 are shown. It will beappreciated that more or fewer heating elements 1110 may be provided inalternative embodiments.

The input material continues to be conveyed by the extrusion screw 1300towards the output end 1104 of the extrusion barrel 1100, where it isejected as a flowable liquid material. In the example illustrated inFIGS. 1 to 9, the material is ejected from the extruder via an ejectionnozzle 1200. More specifically, the flowable material exits the outputend 1104 of the extruder barrel 1100 and enters the input end 1202 ofthe nozzle 1200, flows through the nozzle, and is ejected from theoutput end 1204 of the nozzle.

Optionally, a nozzle heating element (not shown) may also be positionedabout the outer surface of output nozzle 1200. Heat from such a nozzleheating element may be transferred through the nozzle body to theconveyed material via the inner nozzle surfaces, and may be used tocontrol the temperature of the material flowing within the output nozzle1200. It will be appreciated that zero, one, or two or more nozzleheating elements may be provided in alternative embodiments.

The extrusion screw 1300 is rotated by screw drive motor 1030. Screwdrive motor 1030 is preferably an electric motor, such as an alternatingcurrent (AC) motor (asynchronous or synchronous), a direct current (DC)motor, and the like. In the illustrated example, electric motor 1030 isdriven by an adjustable-speed drive 1035, such as a variable-frequencydrive (VFD), adjustable-frequency drive (AFD),variable-voltage/variable-frequency (VVVF) drive, and the like.

The screw drive motor 1030 may be drivingly coupled to the extrusionscrew directly or via a drive transmission member, e.g., an optionalgearbox 1040, which is preferably a reduction gearbox. The use of areduction gearbox may allow the use of a higher-speed, lower powermotor, which may be more efficient and/or less expensive to purchaseand/or operate than a lower speed, higher power motor.

In the example illustrated in FIGS. 1 to 9, the input and output togearbox 1040 are at right angles, allowing motor 1030 to be positionedat an angle to extrusion screw 1300. Alternatively, the input and outputto gearbox 1040 may be on opposite sides of the gearbox, allowing motor1030 to be positioned generally in-line with extrusion screw 1300.Alternatively, the input and output to gearbox 1040 may be at rightangles, but motor 1030 may be positioned beside or below extrusion screw1300. It will be appreciated that gearbox 1040 and/or one or moremechanical or viscous couplings may be provided to allow any suitablerelative position of motor 1030 and extrusion screw 1300.

Extrusion screw 1300 may be rotationally supported within extrusionbarrel 1100 by the gearbox 1040 (or motor 1030, if a gearbox is notprovided) and/or by one or more bearings. For example, at least one endthrust bearing configured to allow rotation of screw 1300, and to resistthe expected axial forces exerted on screw 1300 in a direction towardsthe input end 1302 of the extrusion screw (e.g. due to backpressure ofthe material being conveyed by screw 1300, and/or a partial or completeobstruction of output nozzle 1200) may be provided.

As exemplified, extrusion screw 1300 may be substantially solid.Alternatively, the extrusion screw may be partially or substantiallyhollow. In the illustrated example, the output end 1304 of extrusionscrew 1300 is provided with a nose cone 1310 (see for example FIG. 11).Nose cone 1310 may assist with directing the output material from theoutput end 1104 of the extruder barrel 1100 to the input 1202 of nozzle1200. Nose cone 1310 may optionally be mounted to extrusion screw 1300in a manner that allows it to be axially advanced and retracted relativeto screw 1300, e.g. using an optional knockout rod 1042 that extendsthrough a hollow extrusion screw. The ability to axially advance nosecone 1310 using knockout rod 1042 may be useful when clearing a blockageof output material (e.g. when removing a clogged nozzle 1200).

Extrusion Barrel

Extrusion barrel 1100 preferably has a relatively thin wall thickness,particularly in comparison to barrels used in typical extrusion orinjection molding machines. For example, extrusion barrel 1100 may havea wall thickness of from between 0.015 to 0.375 inches, or from between0.04 to 0.25 inches, or from between 0.08 to 0.1875 inches.

Providing a relatively thin-walled extrusion barrel may have one or moreadvantages. For example, the rate of heat transfer through the extrusionbarrel wall may be proportional to the wall thickness of the barrel,such that a decrease in the barrel wall thickness results in a higherheat transfer rate through the barrel wall. An extrusion barrel 1100having a relatively high heat transfer rate through the barrel wall mayhave one or more advantages. For example, an increased thermal transferrate allows more heat to be transferred through the barrel wall for agiven unit of time. Accordingly, more heat per unit time can betransferred to the plastic material being conveyed through the extrusionbarrel. Thus, it follows that the plastic material needs to spend lesstime in the extrusion barrel to have the necessary amount of heattransferred to it to melt the plastic material and/or less shear heatingis required. As a consequence, if the material is liquefied or the feedmaterial is of a size that seats within the threads of a screw, theextrusion screw 1300 may be rotated at a higher speed (i.e. a higherRPM) to convey the material through the extrusion barrel in a shorteramount of time without incurring excessive pressures that may inhibitthe use of thinner walled barrels.

Extrusion barrel 1100 is optionally made from a material that has arelatively high thermal conductivity, such as copper or aluminum. Usingsuch a material may further increase the heat transfer rate through thebarrel wall, which may provide or enhance one or more of the advantagesnoted above.

Melting Plastic

As discussed previously, in typical extrusion or injection moldingmachines, the heat provided to raise the temperature of the conveyedplastic material as it passes through the extrusion or injection barrelis provided primarily by mechanical shear heating. Further, the barrelwall thickness required to contain the operating pressures required forsignificant shear heating may reduce the maximum heat transfer ratethrough the barrel wall, reducing the amount of energy that can beconveyed to the plastic material via barrel heaters. For example, insome prior art machines, approximately 90% of the total energy suppliedto operate the machine may be supplied to the drive motor, with theremaining 10% being supplied to one or more barrel heaters.

In contrast, during the operation of extruder 1000, a majority, andpreferably a substantial majority, of the heat provided to raise thetemperature of the conveyed plastic material as it passes through theextrusion barrel may be provided by non-mechanical heat sources.

For example, extruder 1000 preferably includes an extrusion barrel 1100having relatively high heat transfer rate through the barrel wall, whichincreases the amount of heat barrel heaters 1110 can provide to theplastic material in a given amount of time. This may allow barrelheaters 1110 to provide at least 60%, 65%, 70%, 75%, 80%, 85%, 90% or atleast 95% of the total amount of heat provided to the conveyed materialduring its time in the extrusion barrel 1100, with the remaining heatbeing provided as a result of mechanical shear heating.

Feed Block

In accordance with an aspect of this disclosure, various differentfeatures of a feed block for an extruder are provided. The shape of theflow passage into and through the feeder may be adjusted. For example,the width of the inlet passage to the screw in the feed block (in adirection transverse to the screw axis) may decrease along part or allof the length of the inlet in the axial direction, the height of thefeed flow passage may decrease along part or all of the inlet passage,and the decrease in height may be constant or it may occur in downwardsteps and/or the shape of the outlet of the feeder in a vertical planelocated at the interface of the feeder and the barrel may be adjusted toprovide a reduced clearance between the screw and the outlet along adownstream portion of the upper end of the outlet. Alternatively, or inaddition, a removable feeder block may be provided. One or more of thesefeatures of the feed block may be used in a feed block, and any suchfeed block may be used by itself or in any combination orsub-combination with any other feature or features described herein.

In accordance with this aspect, a feed block, which may also be referredto as a feeder, includes a feed flow passage, a rotatable screwpositioned in the passage, and a feed block inlet that overlies at leasta portion of the screw. By rotating the screw, a feedstock (e.g. apelletized input material) may be drawn towards a feed block outlet, andfrom there the feedstock may pass into an extrusion barrel of theextruder.

An example of a feed block 1600 will be discussed with referenceprimarily to the examples illustrated in FIGS. 10 to 22. FIG. 10illustrates a feed block 1600 connected to an extruder barrel 1100, andto an optional feed hopper 1020.

With reference to FIG. 11, feed hopper 1020 is optionally positionedabove and in communication with the feed block inlet 1620, so that asfeedstock in a feed flow passage 1630 is drawn towards the feed blockoutlet 1604 in the direction of flow 1625, feedstock (e.g. a pelletizedinput material) loaded in the hopper may be gravity fed into the feedflow passage 1630 via the inlet passage 1620.

Referring to FIG. 21, viewed from above inlet passage 1620 has a lengthL_(inlet) in a direction generally parallel to the axis of screw 1300,which may also be referred to as an axial direction 1625 of the feedflow passage 1630. Inlet passage 1620 also has a width W_(inlet) in adirection generally perpendicular to the axial direction. Asexemplified, the width W_(inlet) of the inlet passage may decrease alongthe length of the inlet in the axial direction (i.e.W_(inlet1)>W_(inlet2)). The width may decrease at a constant rate or thewidth may decrease at an increased rate in the direction of flow 1625.

In the illustrated example, viewed from above a first side 1606 of theinlet passage is generally parallel to the axial direction 1625, andmost of the opposite side 1608 is at an angle Ø to the first side.Notably, the width of the inlet passage 1620 decreases along the lengthof the inlet in the axial direction at a substantially constant rate,with the exception being at the ‘narrow’ end of the inlet passage 1620(e.g. proximate W_(inlet2)), where the sides 1606, 1608 of the inletpassage 1620 converge towards each other at an increasing rate (due tothe rounding of corners 1607 and 1609). Alternatively, corners 1607and/or 1609 may not be rounded, and the width of the inlet passage 1620may decrease along the entire length of the inlet in the axial directionat a constant rate.

As a further alternative, the width of the inlet passage may decreasealong the length of the inlet in the axial direction at an increasingrate. For example, side 1606 of the inlet passage may be generallylinear, and the opposite side 1608 of the inlet passage may have asubstantially arcuate or parabolic shape, when viewed from above.

An advantage of this design is that the inlet passage may preferentiallydirect feedstock material towards one side of the feed flow passage,with this preference increasing in the feed flow direction 1625.Preferably, the side of the feed flow passage towards which feedstock ispreferentially directed is the side at which the feed screw 1300 ismoving downward when the crew is rotated. For example, referring to FIG.13, when feed screw 1300 is rotated in direction 1325, feedstockmaterial from hopper 1020 will be directed by surface 1603preferentially towards downwardly-travelling portions of screw 1300.This may advantageously facilitate a greater portion of feedstockmaterial passing through the inlet 1620 to be directed and preferablycompressed into the volume between the flights 1308 of the screw and theouter surface of screw shaft 1306. For example, feedstock material mayundergo radially inward (e.g. tangential) compaction and/or compressiontowards the outer surface of the screw shaft 1306 between the screwflights 1308 at the region proximate the side of the feed flow passageand the rotating screw 1300 (see e.g. FIG. 15).

Additionally, as the width of the inlet passage 1620 decreases along thelength of the inlet in the axial direction 1625, a greater portion ofthe feed flow passage 1630 may be covered. With reference to FIG. 14,lower surface 1639 is positioned over upwardly-travelling portions ofscrew 1300. This inner surface 1639 of feed flow passage 1630 mayinhibit or prevent material from exiting from between the flights 1308of screw 1300, and/or may inhibit or prevent de-compaction and/ordecompression of material between the flights of screw 1300.Advantageously, this may result in a greater mass of material beingintroduced and/or retained between the screw flights, which may resultin a greater mass flow rate of material in the feed flow direction for agiven rate of rotation (e.g. RPM) of screw 1300.

Referring to FIG. 12, in addition to portions of the feed blockoverlying the feed flow passage along the axial length L_(inlet) of theinlet 1620, an inner surface 1639 of the feed block downstream of theinlet 1620 in the direction of flow 1625 may completely overlie thescrew 1300 to define a downstream or undercut portion 1634 of the feedflow passage 1630.

Alternatively, or in addition to reducing the width of the passage, theheight of the feed flow passage 1630 may be reduced in the downstreamdirection.

As exemplified in FIG. 12, the height of the feed flow passage mayremain constant as the width decreases. As exemplified, surface 1639extends longitudinally generally parallel to the axis of feed screw1300, and generally parallel to the lower surface 1631 of feed flowpassage 1630, resulting in the downstream portion 1634 having agenerally constant volume per unit length in the direction of flow 1625,until a step 1637 proximate the inlet end 1102 of barrel 1100.

Alternatively, or additionally, the height of the feed flow passage maydecrease along part or all of the inlet passage, and the decrease inheight may be constant or it may occur in downward steps. The height ofthe passage may be reduced, with or without reducing the width. Forexample, the surface 1639 may be angled downwardly towards the lowersurface 1631 of feed flow passage 1630. As exemplified in FIG. 12B, theheight of the feed flow passage H_(passage) decreases along the lengthof the feed flow passage in the axial direction 1625 from H₁ at theinlet end to H₂ towards the outlet end. Decreasing the height of thefeedflow passage 1630 in the axial direction 1625 results in thedownstream portion 1634 having a decreasing volume per unit length inthe direction of flow 1625, which may result in increased compactionand/or compression of material as it is drawn by screw 1300 towards thefeed block outlet 1604.

This increased compaction and/or compression may advantageously resultin a greater mass of (e.g. pelletized) input material being introducedand/or retained between the screw flights, which may result in a greatermass flow rate of material in the feed flow direction for a given rateof rotation (e.g. RPM) of screw 1300.

In some embodiments, surface 1639 may be angled towards the lowersurface 1631 of feed flow passage 1630 such that the height of the feedflow passage H_(passage) may decrease along the length of the feed flowpassage in the axial direction 1625 at a substantially constant rate(e.g. as illustrated in FIG. 12B).

Alternatively, surface 1639 may be curved (e.g. a parabolic curve)towards the lower surface 1631 of feed flow passage 1630 such that theheight of the feed flow passage H_(passage) may decrease along thelength of the feed flow passage in the axial direction at an increasingrate.

Alternatively, or additionally, surface 1639 may have one or morediscrete ‘step-downs’ where the height of the feed flow passageH_(passage) may decrease sharply. For example, in the exampleillustrated in FIG. 12, a step 1637 is located proximate the inlet end1102 of barrel 1100. Optionally, step 1637 (or any other step-down alongsurface 1639) may be chamfered, beveled, or curved to decrease thesharpness of the transition.

Alternatively, or additionally, the shape of the outlet of the feeder ina vertical plane located at the interface of the feeder and the barrelmay be adjusted to provide a reduced clearance between the screw and theoutlet along a downstream portion of the upper end of the outlet. Forexample, as perhaps best seen in the example illustrated in FIGS. 24 and25, the inner surface 1639 may have a generally planar portion 1643 anda radially curved portion 1641. Curved portion 1641 results in theradial gap between the outer diameter of screw 1300 and the innersurface 1639 to decrease in the direction of rotation 1325 of the screw1300. This arrangement may result in increasing tangential compressionof input material as it is conveyed towards the extrusion barrel by therotating screw.

For an extrusion screw and barrel used in typical extrusion or injectionmolding machines, the radial gap between the outer screw flight diameterand the inner surface of the extruder barrel is relatively small, forexample, between about 0.001″ and 0.002″. This relatively stringenttolerance may be required to maintain an increased compression of thematerial being extruded (e.g. to facilitate shear heating), and/or toprevent mixing at the barrel wall, which may be considered undesirablein a typical extrusion process.

In contrast, in extruder 1000, the radial gap between the outer diameterof screw 1300 and the inner surface 1106 of extrusion barrel 1100 may bebetween 0.002″ to 0.125″, optionally from between 0.004″ and 0.045″, andoptionally about 0.006 to 0.020″.

In the downstream or undercut portion 1634 of feed flow passage 1630,the gap between the outer diameter of the upper portion of screw 1300and the inner surface 1639 is preferably between 0.020 to 0.750″ morepreferably from between 0.060 and 0.375″, and most preferably about0.125 to 0.250″. Accordingly, the radial volume between the screw 1300and the inner surface of the surrounding feed block is greater than theradial volume between the screw 1300 and the inner surface 1106 ofextrusion barrel 1100. As a result, the input material may be compressedradially inwardly as it is conveyed by the screw through the feed block1600 towards the extrusion barrel 1100.

Adjusting the feed flow passage in one or more of the ways exemplifiedhere may result in less hold-up of the material and a more even flowinto the barrel.

Increasing the compaction and/or compression of the input materialwithin the feed block may result in increased shear heating of thematerial. While shear heating is effective at raising the temperature ofthe feedstock (e.g. plastic) material, there may be one or moredisadvantages. For example, excessive shearing of the plastic materialmay lead to a physical and/or chemical degradation of the polymermolecules within the plastic material. It will be appreciated that whilethe barrel is optionally of a thin wall design as discussed herein, thefeeder and feed block insert may have thicker wall to enable shearing ofthe feedstock prior to its introduction to the barrel.

Also, if the temperature of feedstock material within feed blockincreases too much, there may be a decrease in the mass flow rate for agiven screw RPM. Without intending to be bound by theory, excessiveheating of the material may result in liquefied material with a lowerviscosity, which may negatively affect the screw's ability to convey thematerial efficiently through the barrel and may damage the molecularstructure of the material.

For example, for an ABS feedstock material, the material in the feedblock may preferably have a temperature of between about 10° C. and 35°C. At temperatures of between about 40° C. and 50° C., the mass flowrate for a given screw RPM may decrease, and at temperatures above about55° C., the flow rate may decrease substantially. It is preferred tomaintain a feed block temperature of 0° C. and 50° C., more preferably5° C. and 40° C. and most preferably 10° C. and 35° C.

For example, for a Polyether ether ketone (PEEK) feedstock material, thematerial in the feed block may preferably have a temperature of betweenabout 10° C. and 50° C. At temperatures of between about 65° C. and 75°C., the mass flow rate for a given screw RPM may decrease, and attemperatures above about 85° C., the flow rate may decreasesubstantially. It is preferred to maintain a feed block temperature of0° C. and 70° C., more preferably 5° C. and 60° C. and most preferably10° C. and 50° C.

Optionally, to regulate the temperature of feedstock material that iscompressed as it travels through the feed flow passage, feed block 1600may include a cooling system. Accordingly, a cooling member may beprovided. The cooling member may comprise one or more flow channelsprovided in the feeder.

As exemplified in FIG. 12, the cooling system includes a number ofconduits or coolant flow channels 1690 extending through the feed block.Flow channels 1690 extend between inlet and/or outlet ends 1692, and areconfigured to allow the circulation of a cooling fluid through thecoolant flow channels 1690. As exemplified, coolant flow channels 1690may be each generally linear, and may extend generally transverse to thematerial flow direction 1625. It will be appreciated that any suitableconfiguration of coolant flow channels may be provided in one or morealternative embodiments.

Optionally, the cooling system may include one or more pumps (not shown)to circulate cooling fluid through the coolant flow channels. Thecooling system may also optionally include one or more heat sinks orother passive or active heat exchangers (not shown) through which thecooling fluid may be circulated to remove heat from the fluid beforerecirculating it through the coolant flow channels.

In the example illustrated in FIGS. 10 to 22, feed block 1600 includes amain feed block body 1610 and feed block insert 1605. With reference toFIGS. 17 to 20, feed block insert is preferably removably mounted in afeed throat 1062 of the feed block body 1610. In the illustratedexample, feed block insert 1605 is secured to main feed block body 1610using a plurality of bolts 1698. However, any other securing means orremovable securing means may be used.

Referring to FIGS. 23 to 26, feed block insert 1605 has a downstream end1654, an upstream end 1652, and a lower mounting surface 1653 that isconfigured to be secured against main feed block body 1610. Optionally,one or more sealing members (not shown) may be positioned between mainfeed block body 1610 and feed block insert 1605.

As perhaps best seen in FIGS. 24 and 25, surface 1639 has asubstantially planar portion 1643 and a curved portion 1641. Asdiscussed above, curved region 1641 may result in the radial gap betweenthe outer diameter of screw 1300 and the inner surface 1639 decreasingin the direction of rotation 1325 of the screw, which may promoteincreased tangential compression of input material in and/or proximatethis region.

Referring to FIGS. 18 and 20, the main feed block body 1610 includes achannel defining a lower surface 1631 of feed flow passage 1630. Whenfeed block insert 1605 is mounted to the main feed block body 1610, thischannel and feed block insert 1605 may cooperatively define at least aportion of the feed flow passage 1630. Alternatively, the feeder blockmay define the entire feed flow passage 1630.

In the illustrated example, the inlet passage 1620 of feeder 1600 isdefined by feed block insert 1605 and a surface 1611 of feed throat1062. An advantage of this design is that different feed block inserts1605 may have inlet passages with different geometries. For example, afirst feed block insert 1605 may have an inlet passage 1620 having afirst length L_(inlet), a first width W_(inlet) a first depth D_(inlet)(see e.g. FIG. 25) and one side of the inlet passage may be at a firstangle Ø to the opposite side. A second feed block insert may have alength L_(inlet) that is different than the first length L_(inlet), awidth W inlet that is different than the first width W inlet a depthD_(inlet) that is different from the first depth D_(inlet), and/or oneside of the inlet passage may be at an angle Ø to the opposite side thatis different than the first angle Ø.

Providing feed block inserts 1605 with different geometries may have oneor more advantages. For example, this may allow the geometries of thefeed flow passage 1630 and/or the feeder inlet 1620 of a feed block 1600to be reconfigured by simply replacing the feed block insert with adifferent feed block insert.

Optionally, the geometry of a feed block insert 1605 may be designed toprovide improved and preferably optimized performance for a particularfeed stock material (e.g. plastic composition, particle size, particleshape, elasticity in solid form, etc.) and/or process condition (e.g.screw RPM). Accordingly, a particular feed block insert 1605 may beselected and mounted to feed block body 1610 based on the extrusionprocess to be performed. For instance, a feed stock material that isprovided in the form of a flat flake may feed better when the distancebetween the outer diameter of the upper portion of screw 1300 and theinner surface 1639 is reduced to 0.080 to 0.165″ and the arc towards theside wall may be reduced at a greater rate to improve feeding.Conversely, a feed stock material that is provided in irregular piecesfrom 0.002 to 0.375″ (e.g. typical of regrind material) may feed betterwhen the distance between the outer diameter of the upper portion ofscrew 1300 and the inner surface 1639 is increased to 0.300 to 0.425″and the arc towards the side wall may be reduced at a lesser rate toimprove feeding.

It will be appreciated that some of the embodiments disclosed herein maynot use any of the features of the feed block insert disclosed hereinand that, in those embodiments, a feed block of any kind known in theart may be used.

Use of Multiple Extruders

In accordance with another aspect of this disclosure, which may be usedwith one or more of the aspects of an extruder disclosed herein, two ormore extruders may be used concurrently to fill a mold in a moldingprocess or with an extrusion die.

In accordance with this aspect, the plastic material output from aplurality (i.e. two or more) extruders, which is in a flowable or meltedstate, is directed into a common mold, either directly or via amanifold, which may be a longitudinally flow conduit, connected to themold and to at least some of the extruders.

As discussed above, flowable plastic material may exit each extruder1000 at a relatively low pressure compared to the typical pressures usedin commercial extruders, e.g., typically below 650 psi for fillingmolds, below 1,250 psi for packing molds, whereas typical injectionmolding machines typically inject at 2,500 to 20,000 psi and pack at2,500 to 20,000 psi.

As discussed above, a flowable plastic material may exit extruder 1000at a relatively low pressure, typically below 2,500 psi for producingextruded profiles, sheets or films through a die, and preferably below1,500 psi, whereas typical machines operate at 3,500 to 20,000 psi forproducing extruded profiles, sheets or films through a die.

A further advantage of ‘ganging’ two or more extruders together,preferably about one extruder per foot of width of sheet material thatis to be formed, is that it may reduce the operating pressure within thesystem enabling lighter, smaller, lower cost dies and molds and reducingthe material shearing within nozzles, gates, runners and other die ormold areas, thereby minimizing material degradation and minimizingretrained stress within the final material or part. For example, atypical “coat hanger die” to make a 4 foot wide sheet will be large andcomplex and the pressures to operate it will be in excess of 5,000 psibecause of the long distance that the material must travel within thedie, whereas an extrusion die with one extruder per foot of die length(product width) can operate at 1,500 psi or lower and enables a smaller,far less complex die, faster startup and shut down of the process, lessmaterial shearing within the nozzles, gates, runners and die, therebyminimizing material degradation and minimizing retained stress withinthe final material or part.

In the example illustrated in FIG. 27, extruders 1000 a and 1000 b areeach in fluid communication with a single mold 1500. More specifically,the output ends of the nozzles 1200 a, 1200 b are each fluidicallycoupled to a mold inlet port 1502 a, 1502 b. Mold inlet ports 1502 eachprovide fluid communication to at least one interior mold cavity withinmold 1500, which in the illustrated example is defined by opposing moldhalves 1506 and 1508.

In the example illustrated in FIG. 27, the extruder nozzles 1200 a, 1200b are positioned on opposite sides of mold 1500. Alternatively, theextruder nozzles 1200 may be positioned on opposite ends of mold 1500.For example, as shown in FIG. 28, mold inlet ports 1502 are eachpositioned proximate the junction of the opposing mold halves 1506 and1508.

In the examples illustrated in FIGS. 27 and 28, extruders are positionedon opposite sides of mold 1500. Alternatively, two or more extruders maybe positioned on the same side of a common mold.

Positioning two or more extruders on the same side of a common mold maypose one or more challenges. For example, depending on the size of themold, it may be preferable to have two or more mold inlet portspositioned in relatively close proximity to each other. However,positioning multiple extruders in close proximity to each other (so thattheir respective output nozzles are in close proximity to each other)may present one or more challenges. For example, the overall widths ofthe extruders may prevent their respective output nozzles from being inrelatively close proximity to each other. Additionally, oralternatively, positioning three or more extruders in aside-by-side-by-side arrangement may inhibit or prevent access to the‘middle’ extruder(s).

In one embodiment, extruders having the same length may be utilizedwherein the feeders are staggered. Using extruders having the samelength may permit the use of identical extruders that are used inunison. In such a case, one or more of the extruders may be providedwith an extension conduit 1700 on the output nozzle 1200 such that eachextruder may communicate with the common mold or extrusion die. In sucha case, it will be appreciated that the extension conduit 1700 may beheated to maintain the fluidity of the plastic therein.

For example, as exemplified in FIGS. 29 and 30, extruders 1000 a, 1000b, and 1000 c, each having substantially the same axial length L_(Axial)between their feed inlet 1620 and their output nozzle 1200, arepositioned relative to each other such that extruders 1000 a and 1000 care positioned side-by-side, and extruder 1000 b is offset rearwardly inan axial direction from extruders 1000 a and 1000 c. In the illustratedexample, the output of extruder 1000 b feeds into an inlet end 1702 ofan extension conduit 1700 positioned between extruders 1000 a and 1000c. In this arrangement, a nozzle 1720 at the output end 1704 ofextension conduit 1700 is axially and vertically aligned with theoutputs 1200 a, 1200 c of extruders 1000 a and 1000 c. This mayfacilitate the connection of the outputs 1200 a, 1200 c, and 1720 to acommon mold (not shown).

Extension conduit 1700 is optionally configured to maintain thetemperature of flowable material traveling through the conduit from theoutput nozzle 1200 b of extruder 1000 b to the nozzle or output 1720 ofextension conduit 1700. Optionally, the extension conduit 1700 isthermally insulated, and may optionally include one or more heating orcooling elements to control the temperature of material within theconduit 1700.

In an alternative embodiment, the extruders may be of different lengthsto enable the feeders to be at staggered locations. In such a case, anextension conduit 1700 may not be utilized.

For example, as exemplified in FIGS. 31 to 33, two extruders 1000 a,1000 b, with different axial lengths L_(Axial) between their feed inlet1620 and their output nozzle 1200, are positioned side-by-side. In thisarrangement, the outputs 1200 a, 1200 b of the extruders are axially andvertically aligned with each other. This may facilitate the connectionof the outputs 1200 a, 1200 b to a common mold (not shown).

Alternatively, or in addition to staggering the position of the feeders,with or without using an extension conduit 1700, the plastic materialoutput from a plurality (i.e. two or more) of extruders, which is in aflowable or melted state, may be directed into a heated manifold, whichmay itself be connected to a mold.

For example, as exemplified in FIGS. 34 to 37, six extruders 1000 a-fare each in fluid communication with a common manifold 1800. Asexemplified, the output 1820 of the common manifold 1800 is directlyconnected to a common mold (not shown). Thus, each of the six extruders1000 a-f may be in fluid communication with a common mold via commonmanifold 1800.

More specifically, the output ends of the nozzles 1200 a-f are eachfluidically coupled to a respective manifold inlet port 1812 a-f.Manifold inlet ports 1812 a-f each provide fluid communication to atleast one interior conduit 1830 within manifold 1800, which in theillustrated example is perhaps best shown in FIGS. 36 and 37.

In the illustrated example, the extruders 1000 a-f are arranged relativeto the common manifold 1800 such that the direction of flow of materialthrough the extruder barrels is approximately perpendicular to thedirection of flow of material through the manifold 1800. In other words,with reference to FIG. 35, the angle Ø between the direction of materialflow 1625 through extruder 1000 b and the axial direction of materialflow 1825 through manifold 1800 is about 90°. Alternatively, one or moreextruders may be arranged relative to the manifold 1800 such that theangle Ø is an acute angle (e.g. between about 80° to 10°, or betweenabout 60° to 30°, or between about 50° to 40°, or about) 45°. Providingan acute angle Ø between an extruder 1000 and manifold 1800 may have oneor more advantages. For example, this allows the flowing material toundergo a change of direction of less than 90°, which may reducebackpressure through the manifold conduit 1830 and/or the extruderbarrel 1100.

Using a manifold 1800 with the extruders positioned along part or all ofthe length of the manifold enables the extruders to be spaced apart forease of maintenance. In addition, it permits the feeders to be spacedapart such that each may have a separate hopper or, as discussedsubsequently, it may permit some of the feeders to use a common hopper.

Manifold 1800 is optionally configured to maintain the temperature offlowable material traveling through the one or more conduits 1830. Asthe plastic material exiting the extruders 1000 is in a flowable statedue to its elevated temperature, if the flowable material is allowed tocool, it will begin to solidify, which may not be desirable.

Accordingly, manifold 1800 optionally includes one or more heatingelements 1850 that are operable to maintain the flowable plasticmaterial within the manifold at an elevated temperature (which may bethe same or different than the temperature at which the material exitsthe extruder(s) 1000) so that the plastic material remains in a flowablestate until it exits the manifold. In the example illustrated in FIGS.36 and 37, band heaters 1850 are positioned along the length of conduit1830.

Also, the manifold 1800 is optionally thermally insulated. In theexample illustrated in FIGS. 36 and 37, an insulating layer 1860 ispositioned around the length of conduit 1830 and the band heaters 1850.

In the illustrated examples, flow through the heated conduit 1830 isinduced by the pressure of the flowable plastic material exiting each ofthe extruders 1000. Optionally, the conduit 1830 may be provided withone or more ejection assist members to increase the pressure and/or flowfor material flowing through the conduit.

For example, a rotatable delivery screw (e.g. similar to screw 1300) maybe provided within conduit 1830, and rotation of such the delivery screwmay assist in advancing flowable plastic material towards the output1820 of the conduit 1830.

Alternatively, or in addition, a retractable piston or plunger may beprovided within conduit 1830 (e.g. at the end 1832 of the conduit 1830opposite the conduit output end 1834). Advancement of such a plungertowards the conduit output 1834 (e.g. via one or more mechanical,hydraulic, or pneumatic actuators) may increase the pressure of materialin conduit 1830 (e.g. by reducing the effective volume of conduit 1830).

Providing conduit 1830 with an ejection assist member may have one ormore advantages. For example, once a cavity of a mold connected to theoutput of conduit 1830 is filled (or almost filled) with flowableplastic material (e.g., 75%, 80%, 85%, 90%, 95% or more filled), theejection assist member may be actuated to increase the pressure ofmaterial in conduit 1830, which may increase the pressure of thematerial in the mold. Such an arrangement may allow for large and/orcomplex mold cavities to be filled using a relatively low-pressureoutput from an extruder, and subsequently subjected to higher pressuresthat may be required or desirable to properly fill the mold and/or tocompress the flowable material within the mold cavity to improve one ormore physical properties of the molded component.

Another possible advantage of this approach relates to the production ofmolded components with relatively complicated geometries, and/or theproduction of relatively large molded components. In this respect, sincethe molding process outlined above does not rely on the output oroperating pressure of the extrusion barrels to provide the maximumpressure on the flowable material within the mold cavity (insteadrelying on one or more ejection assist members within the conduit 1830),such a molding process may be ‘scaled up’ to provide higher moldingpressures (e.g. for use with molds with relatively complex internalcavities and/or with molds for relatively large molded components)without having to ‘scale up’ the operating pressure of the extruders.

In some embodiments, where multiple extruders are in communication witha common mold (e.g. via a heated manifold or conduit 1830), the inputmaterial for each extruder may be the same. For example, pelletizedfeedstock of the same polymer may be fed in to each extruder, such thatthe output from each extruder and the output from the common manifoldgenerally has the same composition.

Optionally, one or more extruders in communication with a commonmanifold may be provided with a different input material than the otherextruder(s). For example, one or more extruders may be fed a differentpolymer feedstock than one or more of the other extruders. This canenable the production of an inner core of material with a glass filedmaterial for strength and an outer layer without any filler to create alubricious outer surface. Similarly, one extruder can provide a colourfor a stripe of a product while the second extruder provides the corecolour for the product. Additionally, or alternatively, one or moreextruders may be concurrently fed with both a polymer feedstock and oneor more additives (e.g. a color dye, a stabilizing agent, anantioxidant, a flame retardant, etc.) while one or more of the otherextruders may only be fed with a polymer feedstock.

Providing an apparatus that allows an additive to be provided in one ormore extruders may have one or more advantages. For example, providingcolor dye(s) in only some of the extruders in communication with acommon manifold may result in an aesthetically different molded orextruded component than if the output from each extruder was similarlydyed (e.g. the color of the material output from the conduit may not behomogenous). As another example, if an additive is no longer used (e.g.if the apparatus is transitioned to produce different components), onlythe extruder(s) in which the additive was used may need to be cleanedout before transitioning to the new input material.

Optionally, a mechanical mixing or blending member (not shown) may beprovided in flow communication between the heated manifold 1800 and amold to be filled by the material exiting the heated manifold. Forexample, a static mixer and/or a driven gear mixer (not shown) may beprovided at the output end 1834 of the conduit 1830, either upstream ordownstream of output nozzle 1820.

Providing a mechanical mixer downstream of the output of each extruderconnected to the common manifold 1800 may have one or more advantages.For example, such a mixer may promote a relatively homogenous outputmaterial from the conduit 1830, even where some of the extruders 1000connected to the common manifold are provided with a different inputmaterials and/or additives.

If two or more extruders are utilized, then a common hopper may be usedfor at least two of the feeders. For example, extruders that havefeeders positioned proximate each other may use a common hopper. Anadvantage of such a design is that it may maintain a common headpressure of material above the different screws so as to maintain a moreconsistent feed rate. Also, it may make filing of the system easier.

For example, as exemplified in FIGS. 34 to 37, input material is loadedinto the inlet hopper 1020 of each extruder 1000. However, the ‘middle’extruders 1000 b and 1000 e—and particularly their inlet hoppers 1020 band 1020 e—may be at least somewhat challenging to access, particularlyas compared to the inlet hoppers of extruders 1000 a, 1000 c, 1000 d,and 1000 f. Optionally, the feed inlets of two or more extruders may beconnected to a common feed hopper.

FIGS. 38 and 39 illustrate an example apparatus in which pairs ofextruders 1000 provided on an opposite side of a manifold are providedwith a common feed hopper. In the illustrated example, a common hopper2020 a is connected to the inlet passages 1620 a, 1620 f of extruders1000 a, 1000 f, such that input material loaded into the common hopper2020 a may be directed to one of the two extruders 1000 a, 1000 f. Also,a common hopper 2020 b is connected to the inlet passages 1620 b, 1620 eof extruders 1000 b, 1000 e, and a common hopper 2020 c is connected tothe inlet passages 1620 c, 1620 d of extruders 1000 c, 1000 d.

FIGS. 40 and 41 illustrate an example apparatus in which pairs ofextruders 1000 on the same side of a manifold are provided with commonfeed hoppers. In the illustrated example, a common hopper 2020 a isconnected to the inlet passages 1620 a, 1620 f of extruders 1000 a, 1000f, a common hopper 2020 b is connected to the inlet passages 1620 b,1620 c of extruders 1000 b, 1000 c, and a common hopper 2020 c isconnected to the inlet passages 1620 d, 1620 e of extruders 1000 d, 1000e.

Providing a common hopper for two or more extruders may have one or moreadvantages. For example, it may allow two extruders to be loaded from asingle feed location.

It will be appreciated that some of the embodiments disclosed herein maynot use any of the features of the heated conduit disclosed herein andthat, in those embodiments, a conduit of any kind known in the art maybe used.

Modular Extruder

In accordance with another aspect of this disclosure, a bench scaleextruder as disclosed herein may be of a modular design. Using modularcomponents that are readily assemblable and disassemblable permits anextruder to be shipped as individual components and assembled on sitewithout the need of a skilled tradesperson. These features may be usedby themselves or in any combination or sub-combination with any otherfeature or features described herein.

In accordance with this aspect, an extruder 1000 may be assembled from(and preferably disassembled into) a relatively low number of parts ormodules. A modular extruder design may have one or more advantages. Forexample, assembly of such an extruder may be relatively simple, whichmay reduce time and/or cost required to install the extruder on site.

Optionally, in some embodiments, extruder 1000 includes at least fourmodular components. Specifically, a modular extruder may include anextruder barrel module, an extruder feeder module, a screw motor module,and an electronics module. Advantageously, a design including thesemodular components may allow one or more of these modular components tobe provided in different variations, which may allow a large number ofextruder configurations to be provided by selecting desired combinationsof modular components. For example, a different screw motor module (e.g.a module with a 5 hp motor, or a module with a 2.5 hp motor, etc.) maybe selected based on a desired operating speed and/or torque of the feedscrew 1300 of extruder 1000. As another example, a different barrellength (e.g. 36″, or 48″, etc.) may be selected based on the material tobe extruded. By providing at least these four main components ofextruder 1000 in a modular configuration, a number of possible extruderconfigurations may be assembled.

With reference to FIG. 9, in the illustrated example extruder 1000 isshown in a partially disassembled configuration. A barrel module maycomprise barrel heaters 1110 and output nozzle assembly 1200 that areprovided on barrel 1100. Optionally, the screw 1300 may be part of thebarrel module or may be a separate element. For example, if the screw1300 extends into the flow passage of the feeder and the barrel, thenthe screw may be part of the barrel module, the feeder module, the screwmotor module, or a separate component.

Barrel module is removably connectable to an extruder feeder module toprovide flow communication between the interior of barrel 1100 and aninternal flow passage 1630 of the feed block 1600. As exemplified inFIG. 9, extruder 1000 includes a feed block 1600 (which, as discussedabove, may optionally include a feed block insert 1605), and a hopper1020. In this example, feed block 1600 may be characterized as anextruder feeder module. Alternatively, the hopper 1020 may be secured tofeed block 1600, and the combined hopper and feed block may becharacterized as an extruder feeder module.

The barrel module may be coupled, and optionally releasably coupled, tothe extruder feeder module using a threaded connection. Specifically,barrel 1100 may have an external threaded section 1103 at the inlet end1102 and extruder feed block 1600 may include a threaded port 1613positioned at the outlet end 1604 of the internal flow passage 1630 ofthe feed block 1600. Threaded port 1613 is configured to receive thethreaded barrel end 1103.

An extruder feeder module may also be removably connectable to a screwmotor module. The screw motor module is the module that provides motiveforce to the screw 1300 and, optionally, may include the screw 1300. Asexemplified in FIG. 9, extruder 1000 includes a combined or integratedgear box 1040 and drive motor 1030, and an adjustable-speed drive 1035.In this example, the gearbox 1040 and motor 1030 may be characterized asa screw motor module. Alternatively, adjustable-speed drive 1035 may besecured to the combined gear box 1040 and drive motor 1030, and thecombined motor drive, motor, and gearbox may be characterized as a screwmotor module.

In the illustrated example, a screw motor module may be coupled to anextruder feeder module using a plurality of bolts 1699 (see e.g. FIGS.17, 21, and 22). Optionally, with reference to FIGS. 12 and 22, screw1300 may be positioned in the internal flow passage 1630 of the feedblock 1600 such that a drive engaging end 1344 of the screw 1300 isaccessible from the motor mounting end 1684 of the extruder feedermodule. The drive engaging end 1344 of screw 1300 may be coupled to ascrew motor module using any suitable method known in the art, such as athreaded coupling, a keyed joint, and the like.

As exemplified in FIG. 9, extruder 1000 includes user input devicesand/or control electronics enclosed in a control housing or cabinet1010.

In this example, housing 1010 and the control electronics housed thereinmay be characterized as an electronics module. In the illustratedexample, the electronics module may be mechanically secured to one ormore other modules and/or to an extruder base 1005 (as discussedsubsequently), and may be configured to ‘straddle’ the extruder barrel1100. Notably, in the illustrated example this allows lower portions ofhousing 1010 to act as a housing or shroud for barrel 1100.

The electronics module is optionally electrically connectable with thebarrel module, e.g. to power and/or control the operation of bandheaters 1110. The electronics module is also optionally electricallyconnectable with the screw motor module (e.g. with drive motor 1030and/or adjustable-speed drive 1035) to control the operation of motor1030, thereby controlling the rotation of screw 1300. Optionally, theelectronics module may be indirectly electrically connectable with thescrew motor module via electrical wiring associated with the extruderfeeder module (e.g. a wiring harness mounted internally or externally tofeed block 1600).

Optionally, the electronics module may be automatically electricallyconnectable with the barrel module and/or the screw motor module (e.g.with drive motor 1030 and/or with adjustable-speed drive 1035) when theelectronics module is mounted as part of the extruder 1000.

For example, an electrical connector (not shown) operatively connectedto electronic components of the screw motor module may be providedadjacent the mounting location between the screw motor module and theextruder feeder module. A mating electrical connector (not shown)operatively connected to the electronics module may also be providedadjacent this mounting location. In such an arrangement, aligning andmechanically coupling the extruder feeder module and the screw motormodule may result in engagement of the electrical connectors of thescrew motor module and the extruder feeder module (e.g., one connectormay be ‘female’, and the other may be ‘male’). Aligning and mechanicallycoupling the electronics module to the extruder feeder module may resultin engagement of the electrical connectors of the electronics module andthe extruder feeder module and, indirectly, connect the electronicsmodule with the screw motor module.

Additionally, or alternatively, the barrel module may be automaticallyelectrically connected to the feeder module in a similar way. Aligningand mechanically coupling the electronics module to the barrel modulemay result in engagement of the electrical connectors of the electronicsmodule and the barrel module and, indirectly, connect the electronicsmodule with the screw motor module via the feeder module.

The extruder 1000 may be secured to any base. For example, the extruder1000 may be mechanically secured to an extruder base 1005, which in theillustrated example is a length of C channel steel. This may facilitatethe installation of extruder 1000 within a workplace. For example, base1005 may be secured to a floor surface or other mounting location, andthe modular components of extruder may be installed on the base. It willbe appreciated that one or more of the modules, e.g., the barrel module,may be secured to base 1005 (with the other modules being secureddirectly or indirectly to the module(s) that are secured to the base1005), and base 1005 may subsequently be secured to a floor surface orother mounting location.

Optionally, screw 1300 may be a single integrally formed screw.Alternatively, an extrusion screw 1300 may be made from two or moreparts. For example, an extrusion screw 1300 may include a feeder screwbody section and a barrel screw body section. Feeder and barrel screwbody sections may be joined using any suitable method, such as athreaded coupling, a keyed joint, welding and the like. In suchembodiments, a feeder screw body section may be secured to extruder feedblock 1600 or to the screw motor module, and a barrel screw body sectionmay be coupled to the feeder screw body section before, after, orconcurrently to coupling the barrel module to the extruder feedermodule.

Providing a multi-part screw with a feeder screw body section secured toan extruder feeder module or to a screw motor module may have one ormore advantages. For example, such an arrangement may facilitate properalignment of screw 1300 within feed flow passage 1630 and/or barrel1100, and/or reduce the time needed to assemble extruder 1000. It mayalso permit the screw to be shipped internal of the modules and therebybe protected during shipment.

As noted above, a modular extruder design may have one or moreadvantages. For example, the overall weight and dimensions of eachmodule may result in their being shippable by a commercial couriercompany (e.g. FedEx, UPS, etc.) without excessive overweight and/oroversize surcharges. For example, each module may weigh less than under175 lbs, 150 lbs, 135 lbs, or 100 lbs.

It will be appreciated that some of the embodiments disclosed herein maynot use any of the features of the modular extruder disclosed herein andthat, in those embodiments, an extruder of any suitable construction maybe used.

As used herein, the wording “and/or” is intended to represent aninclusive - or. That is, “X and/or Y” is intended to mean X or Y orboth, for example. As a further example, “X, Y, and/or Z” is intended tomean X or Y or Z or any combination thereof.

While the above description describes features of example embodiments,it will be appreciated that some features and/or functions of thedescribed embodiments are susceptible to modification without departingfrom the spirit and principles of operation of the describedembodiments. For example, the various characteristics which aredescribed by means of the represented embodiments or examples may beselectively combined with each other. Accordingly, what has beendescribed above is intended to be illustrative of the claimed conceptand non-limiting. It will be understood by persons skilled in the artthat other variants and modifications may be made without departing fromthe scope of the invention as defined in the claims appended hereto. Thescope of the claims should not be limited by the preferred embodimentsand examples, but should be given the broadest interpretation consistentwith the description as a whole.

The invention claimed is:
 1. A feeder for an extruder, the feedercomprising: (a) a feed flow passage, the feed flow passage extending inan axial direction from a first end to an axially spaced apart secondend that is connectable in flow communication with a barrel of theextruder; (b) an axially extending rotatable screw provided in the feedflow passage, wherein rotation of the screw draws a feedstock in adirection of flow to the second end; and, (c) the feed flow passage hasan inlet that overlies the screw, the inlet comprising an opening in apassage wall of the feed flow passage, the opening extending in theaxial direction from a first opening end proximate the first end of thefeed flow passage to an axially spaced apart second opening endproximate the second end of the feed flow passage, the opening having alength in the axial direction and a width in a plane transverse to theaxial direction, wherein the width decreases from a first width at thefirst opening end to a second width at the second opening end, whereinthe width decreases at an increased rate in the axial direction alongthe entire length of the opening.
 2. The feeder of claim 1 furthercomprising a hopper having a hopper outlet and the inlet is providedbelow the hopper outlet.
 3. The feeder of claim 1 further comprising acooling member.
 4. The feeder of claim 3 wherein the cooling membercomprises cooling channels provided in thermal communication with thefeed flow passage.
 5. The feeder of claim 1 further comprising a feederinsert that is removably mounted in a feed throat of the feeder, whereinthe feeder insert has the inlet.
 6. The feeder of claim 5 wherein thefeeder removably receives different feeder inserts, wherein a firstfeeder insert has a first inlet and the second feeder insert has asecond inlet wherein the width of the second inlet varies at a differentrate in the axial direction to the width of the first inlet.
 7. Thefeeder of claim 6 wherein each inlet has an upstream end in the axialdirection and a downstream end in the axial direction and the secondinlet has a narrower width at the downstream end of the second inletthan the width at the downstream end of the first inlet.
 8. The feederof claim 1 wherein the feed flow passage has a height perpendicular tothe axial direction, the height extending between the opening in thepassage wall of the feed flow passage and a lower surface of the feedflow passage, the height decreases from a first length at the firstopening end to a second length at the second opening end.
 9. The feederof claim 8 wherein the height decreases at a constant rate.
 10. Thefeeder of claim 8 wherein the height decreases at an increased rate.